Truncated L1 protein of human papillomavirus type 11

ABSTRACT

The invention relates to a truncated L1 protein of the Human Papillomavirus Type 11, a virus-like particle consisting of the protein, a vaccine comprising said virus-like particle, and the use of the vaccine in the prevention of condyloma acuminatum or HPV infections.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Phase of PCT/CN2008/001049, filed May 29, 2008, which in turn claims priority to Chinese Patent Application No. 200710105763.2, filed May 29, 2007, the contents of both of which are incorporated herein in their entirety by reference.

FIELD OF THE INVENTION

The invention relates to a truncated L1 protein of the Human Papillomavirus Type 11, a virus-like particle consisting of the protein, a vaccine comprising said virus-like particle, and the use of the vaccine in the prevention of condyloma acuminatum and HPV (especially HPV11) infection.

BACKGROUND OF THE INVENTION

The human papillomavirus, a non-enveloped, deoxyribonucleic acid (DNA) virus, belongs to the genus of papovaviridae. The viral genome is a closed circle, double-stranded DNA, which is approximately 7.2-8 kb in length and contains 8 open reading frames (ORFs). The genome can be divided into three parts in terms of function: (1) the early region (E), approximately 4.5 Kb in length, coding for 6 non-structural proteins E1, E2, E4˜E7 associated with virus replication, transcription and transformation; (2) the late region (L), approximately 2.5 Kb in length, coding for the major capsid protein L1 and the minor capsid protein L2; (3) the long control region (LCR), located between the end of the L region and the initiating terminal of the E region, approximately 800-900 bp in length, and comprising regulator elements for DNA replication and expression instead of coding for proteins. Viral particles are 45-55 nm in diameter, wherein the nucleocapsid, consisting of L1 and L2, exhibits icosahedral symmetry and comprise 72 capsomers.

Currently, there are over 90 different types of HPV, mainly causing papillary disease in the skin and mucosa of human. HPV types are divided into three groups depending on their relation with tumorigenesis: (1) group of low or no cancerogenic risk, containing types 6, 11, 39, 41, 42, and 43; (2) group of medium cancerogenic risk, containing types 31, 33, 35, 51, and 52; and (3) group of high cancerogenic risk, containing types 16, 18, 45, and 56.

Epidemiological investigation reveals that HPV (such as HPV6, 11) infection in the anal-genital mucosa is the third most common sexually transmitted disease following trichomoniasis and chlamydia. Pathological changes caused by HPV types 6 and 11 account for about 90% of these cases. In America, HPV infection of genital meatus among women occurs most frequently when they are 15-25 years old and is highly related to the infected person's sexual behavior. In China, HPV infection among women occurs most frequently when they are 20-29 years old, and the infection rate is 1606.1/100,000. Women are less infected with HPV as they grow older than 35. However, since the majority of HPV infections are sub-clinical, it is difficult to accurately estimate the infection rate. As estimated by the US CDC, the risk is approximately 10% during the whole life. In addition, there is little data regarding HPV infection among men, due to the difficulty of sample collection and the lesser severity of consequences. Currently, HPV infection rate among men is believed to be close to the one among women. In the United States, condyloma acuminatum can be found in 1% of sexually active adult men. Therefore, the development of a safe, efficient vaccine for HPV 6 and 11 would be an effective way to prevent sexually transmitted diseases.

HPV L1 protein, with a molecular weight of 55-60 kDa, is the major capsid protein of the human papillomavirus and the main target protein of the HPV vaccine. HPV L1 protein expressed in multiple different expression systems can form Virus-like particles (VLPs) which resemble native HPV particles morphologically, without the assistance of the L2 protein. The VLP, consisting of 72 pentamers of the L1 proteins, exhibits icosahedral symmetry. Since the VLPs retain the native epitopes of the viral particles, they are highly immunogenic and can induce the generation of neutralizing antibodies against homologous HPV (Kirnbauer, R., F. Booy, et al. 1992 Proc Natl Acad Sci USA 89(24): 12180-4). Furthermore, the VLPs are safe and have no potential cancergenic risk as they contain no viral DNA. Therefore, VLP vaccines become the primary candidate for an HPV vaccine.

The key for development of a vaccine is to efficiently produce VLP vaccines of HPV in large-scale. Currently, the most commonly used expression systems are eukaryotic expression systems and prokaryotic expression systems.

The commonly used eukaryotic systems comprise poxvirus, insect baculovirus and yeast vectors. HPV L1 protein expressed in eukaryotic systems shows little conformational difference from that of the native virus, and can self-assemble into VLPs. Thus, purified VLPs can be easily obtained after gradient density centrifugation. It brings a lot of convenience to the purification work. However, due to the high culture costs and low expression level, it is quite difficult to product industrially on a large-scale. The HPV vaccine Gardasil®, which came into the market recently, is more expensive than others due to low expression level and high production cost of the Saccharomyces cerevisiae expression system employed in its manufacture.

The expression of HPV L1 protein in a prokaryotic system such as E. coli has been previously reported. Banks, Matlashewski, et al. published a paper regarding the expression of HPV 16 L1 by employing E. coli (Banks, L., G. Matlashewski, et al. (1987). J Gen Virol 68 (Pt 12): 3081-9). However, most HPV L1 proteins expressed by E. coli lose their native conformation and cannot induce the generation of protective antibodies against HPV. Alternatively, although HPV VLPs can be obtained from the incorrectly folded proteins by steps such as purification from inclusion bodies and refolding, it is difficult to apply this method to large-scale production, as the protein is largely lost during the refolding process and the yield is low (Kelsall, S. R. and J. K. Kulski (1995). J Virol Methods 53(1): 75-90). Although HPV L1 protein may be expressed in a soluble form with a correct conformation in E. coli and dissolved in the supernatants of E. coli lysate, the expression level is low. Moreover, since there are large number and amount of impure proteins, it is difficult to isolate the proteins of interest from them. Although it is reported that the expression level of L1 protein can be increased in the supernatants by means of GST fusion expression and the purification of the protein of interest is facilitated (Li, M., T. P. Cripe, et al. (1997), J Virol 71(4): 2988-95), it still cannot be applied to large-scale production because expensive enzymes are required to cleave the fusion protein.

Therefore, a HPV L1 protein capable of inducing the generation of protective antibodies against HPV, and a virus-like particle consisting of the same are still needed in the art, so that it is possible to produce vaccines for condyloma acuminatum industrially on a large scale.

DESCRIPTION OF THE INVENTION

This invention aims to provide a novel HPV type 11 L1 protein, the virus-like particles (VLPs) consisting of it, and a vaccine comprising the VLPs.

During research, it was found by chance that the E. coli expression system can produce a truncated HPV 11 L1 protein that can induce the generation of neutralizing antibodies against HPV 11. After purification, the truncated HPV11 L1 protein can be produced in high yield, with at least 50% purity. Further treatment of the purified HPV L1 protein can produce VLPs, which can induce the production of neutralizing antibodies against HPV 11. The invention has been completed based on the above.

Therefore, the first aspect of the invention relates to HPV 11 L1 proteins with 3, 4, 5, or 6 amino acids truncated at N-terminal as compared to a wild type HPV 11 L1 protein. Preferably, the truncated protein has the sequence set forth in SEQ ID Nos:1, 2, 3, or 4, especially the sequence set forth in SEQ ID NO:1.

A further aspect of the invention relates to a polynucleotide encoding the truncated protein according to the invention, and a vector containing the polynucleotide.

A further aspect of the invention relates to a cell comprising the vector.

The invention also relates to a composition comprising the truncated protein, the polynucleotide, the vector, or the cell.

A further aspect of the invention relates to a HPV 11 VLP, comprising or consisting of a HPV 11 L1 protein with 3, 4, 5, or 6 amino acids truncated at the N terminal such as a HPV 11 L1 protein having a sequence set forth in SEQ ID NOs: 1, 2, 3, or 4.

A further aspect of the invention relates to a method for obtaining the HPV 11 L1 protein, comprising the expression of a truncated HPV 11 L1 gene fragment in an E. coli system and the subsequent purification of the protein from the lysate supernatant.

In a preferred embodiment of the invention, a method for obtaining HPV 11 L1 protein comprises:

-   -   a) expressing the truncated HPV 11 L1 gene fragment in a E. coli         expression system;     -   b) disrupting E. coli, which has expressed the truncated HPV 11         L1 protein, in a salt solution at a concentration of from 100 mM         to 600 mM, and isolating the supernatant;     -   c) decreasing the salt concentration of the supernatant in b) to         from 100 mM to 0, inclusive, by using water or a low salt         solution, and collecting a precipitate;     -   d) redissolving the precipitation in c) in a salt solution at a         concentration of from 150 mM to 2500 mM, with a reductant added,         and then isolating the resultant solution, wherein the solution         contains the truncated HPV 11 L1 protein with a purity of at         least 50%.

More generally, the invention also relates to a method for obtaining a HPV L1 protein, such as the HPV 11 L1 protein according to the invention, comprising:

-   -   a) expressing a HPV L1 gene encoding the HPV L1 protein in an E.         coli expression system;     -   b) disrupting E. coli, which has expressed the HPV L1 protein,         in a salt solution at a concentration of from 100 mM to 600 mM,         and isolating the supernatant;     -   c) decreasing the salt concentration of the supernatant in b) to         from 100 mM to 0, inclusive, by using water or a low salt         solution, and collecting a precipitate;     -   d) redissolving the precipitation of c) in a salt solution at a         concentration of from 150 mM to 2500 mM, with a reductant added,         and then isolating the resultant solution, wherein the solution         contains the HPV L1 protein with a purity of at least 50%.

The invention also relates to a vaccine for the prevention of condyloma acuminatum or HPV infection, comprising VLPs of HPV 11 L1 proteins according to the invention. Preferably, the vaccine further comprises at least one VLPs selected from VLPs of HPV18, 6, 16, 31, 33, 45, 52, and 58 L1 proteins. Generally, the vaccine further contains carriers or excipients useful for vaccine.

Preferably, the vaccine comprises HPV 6 VLPs and HPV 11 VLPs, especially the HPV 6 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 7, and the HPV 11 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 1. More preferably, the vaccine further comprises HPV 16 VLPs and HPV 18 VLPs, especially the HPV 16 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 8, and the HPV 18 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 9.

In a specially preferred embodiment, the vaccine comprises the HPV 6 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 7, the HPV 11 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 1, the HPV 16 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 8, and the HPV 18 VLPs comprising or consisting of a protein having an amino acid sequence set forth in SEQ ID No: 9.

The invention further relates to the use of the HPV 11 L1 protein or the VLPs thereof in the manufacture of a vaccine for the prevention of condyloma acuminatum or HPV infections.

The invention further relates to a method for preventing condyloma acuminatum or HPV infections, comprising administrating a vaccine comprising an preventively effective amount of HPV 11 L1 protein to a human or animal in need of preventing condyloma acuminatum or HPV infections.

The invention involves a method for obtaining VLPs of the HPV 11 L1 protein, comprising:

-   -   e) further purifying the truncated HPV 11 L1 protein with a         purity of at least 50% by subjecting it to a chromatography;     -   f) removing the reductant from the HPV 11 L1 protein obtained in         e).

This invention involves a method for preparing a vaccine for preventing condyloma acuminatum or HPV infections, comprising blending the VLPs above, and optionally, one or more VLPs selected from the group consisting of VLPs of HPV 6, 16, 18, 31, 33, 45, 52 and 58, with carriers or excipients useful for vaccines.

DEFINITIONS OF THE TERM IN PRESENT INVENTION

According to the invention, the term “E. coli expression system” refers to a expression system consisting of E. coli (strains) and vectors, wherein the E. coli (strains) include, but are not limited to: GI698, ER2566, BL21 (DE3), B834 (DE3), and BLR (DE3), which are available on the market.

According to the invention, the term “vectors” refers to the nucleic acid carrier tools which can have a polynucleotide encoding a protein inserted therein and allow for the expression of the protein. The “vector” can have the carried genetic material expressed in a host cell by transformation, transduction, and transfection into the host cell. For example, “vectors” include plasmids, phages, cosmids and the like.

According to the invention, the term “a gene fragment of a truncated HPV 11 L1 protein” refers to the nucleic acids with the nucleotide(s) encoding one or more amino acid sequences deleted at 5′ or 3′ terminal of the wild-type HPV 11 L1 gene (cDNA). The full-length gene sequence of the wild-type HPV 11 L1 gene can be found in, but not limited to, the following NCBI sequences: M14119.1, AF335603.1 and AF335602.1.

The term “truncated HPV 11 L1 protein” refers to the protein with one or more amino acids deleted at the N- and/or C-terminal of the wild-type HPV 11 L1 protein. The full-length gene sequence of the wild-type HPV 11 L1 protein can be found in, but not limited to, the full-length L1 proteins encoded by the following NCBI sequences: M14119.1, AF335603.1 and AF335602.1.

According to the invention, the term “carriers or excipients useful for vaccines” refers to one or more reagents, including but not limited to: pH regulators, surfactants, adjuvants, and ionic strength enhancers. For example, pH regulators include, but are not limited to, phosphate buffers; surfactants include, but are not limited to: anion surfactants, cation surfactants, non-ionic surfactants (for example, but not limited to Tween-80); adjuvants include, but are not limited to, aluminum hydroxide and Freund's complete adjuvant; and Ionic strength enhancers include, but are not limited to, NaCl.

According to the invention, the term “chromatography” includes, but is not limited to: ion exchange chromatography (e.g. cation-exchange chromatography), hydrophobic interaction chromatography, absorbant chromatography (e.g. hydroxyapatite chromatography), gel filtrate chromatography (gel exclusion chromatography), and affinity chromatography.

According to the invention, the truncated HPV 11 L1 proteins may be obtained preferably by the following steps:

-   -   a) disrupting E. coli, which expresses truncated HPV 11 L1         protein, in a buffer containing 100-600 mM salt, preferably         200-500 mM;     -   b) isolating the supernatant from the disrupted solution, then         decreasing the salt concentration of the supernatant to 100         mM-0M with water or a low-salt buffer (generally, with a salt         concentration lower than the one of the buffer for disrupting);     -   c) separating a precipitant from the supernatant with a salt         concentration as low as 100 mM-0;     -   d) redissoving the precipitant in a solution containing a         reductant and having a salt concentration of 150-2000 mM,         preferably greater than 200 mM;     -   e) isolating a solution of the truncated HPV 11 L1 proteins with         a purity of at least 50%, preferably at least 70%, more         preferably at least 80%.

According to the invention, in the method for obtaining the truncated HPV 11 L1 proteins, the term “buffer” refers to a solution which can maintain pH value stable within a certain range, including but not limited to: Tris buffers, phosphate buffers, HEPES buffers, and MOPS buffers.

According to the invention, the disrupting of the prokaryotic host cell may be achieved by methods including, but not limited to one or more of homogenizer disrupting, ultrasonic treatment, grinding, high pressure extrusion, and lysozyme treatment.

According to the invention, in the method for obtaining the truncated HPV 11 L1 proteins, the salts used include, but are not limited to: one or more of neutral salts, especially alkali metal salt, ammonium salts, hydrochlorides, sulfates, bicarbonates, phosphate salts or hydrogenphosphates, especially NaCl, KCl, NH₄Cl, (NH₄)₂SO₄. NaCl are preferred. The reductant used includes, but is not limited to, DTT and 2-mercaptoethanol, in an amount of including, but not limited to, 10-100 mM.

According to the invention, the VLPs of the truncated HPV 11 L1 protein may be produced by the following steps: further purifying the truncated HPV L1 protein with a purity of at least 50% by subjecting it to a chromatography, and thereby obtaining a purified truncated HPV 11 L1 protein solution; and removing the reductant from the purified HPV 11 L1 protein solution, and thereby obtaining the VLPs of the truncated HPV 11 L1. Methods for removing the reductant include, but are not limited to, known techniques in the art, such as dialysis, ultrafiltration, and chromatography.

According to the invention, the truncated HPV L1 protein preferably has the sequence set forth in SEQ ID NO:1.

According to the invention, the vaccine may be administrated in a patient-acceptable form, including but not limited to oral and injection, preferably injection.

According to the invention, the vaccine is preferably used in a unit dose. Each unit dose contains 5-80 μg truncated HPV 11 L1 VLP, preferably 20-40 μg.

BENEFICIAL EFFECT

Presently, the expression systems useful for preparing HPV VLPs include eukaryotic and prokaryotic expression systems.

HPV L1 proteins expressed in eukaryotic expression systems retain their native conformation, and can form VLPs on their own. In most cases, VLP with a correct conformation can be obtained by simple purification. Nevertheless, eukaryotic expression systems, such as the baculovirus and yeast expression systems, are difficult to be applied in large-scale industrial production due to low expression levels and high costs.

Prokaryotic expression systems, such as E. coli systems, have the advantages of high expression levels at a lower cost. However, when expressed in a prokaryotic system, the HPV L1 protein usually loses its native conformation and is expressed in a form of inclusion bodies in the precipitant. Renaturation of the protein from inclusion bodies is still a problem worldwide. Due to the difficulty and inefficiency of renaturation, this method is limited to small-scale lab research and cannot be applied on a large scale so as to obtain VLP with a correct conformation from the inclusive bodies. Although the HPV L1 protein can exist in its native conformation in the supernatant of E. coli lysate, its expression levels are low. Moreover, it is quite difficult to purify the HPV L1 protein from the numerous soluble proteins in the E. coli lysate supernatant. Generally, the purification is completed by means such as fusion expression and affinity chromatography which are not feasible for industrial-scale processes due to expensive enzymes employed therein.

In this invention, N-truncated HPV 11 L1 protein is expressed in an E. coli expression system and is selectively precipitated from the E. coli lysate supernatant under mild conditions. The HPV 11 L1 protein is then redissolved in a salt buffer to significantly improve its purity while still retaining its native conformation. The redissolved protein of interest can be immediately subjected to ion-exchange or hydrophobic interaction chromatography so as to obtain the pure protein. The purified, truncated HPV 11 L1 protein obtained from these steps, can self-assemble into VLPs with good immunogenicity and the ability to induce neutralizing antibodies of a high titer against HPV 11, which is a good vaccine for preventing human from HPV 11 infection. In addition, the truncated HPV 11 L1 protein used in the present invention, with the antigenicity and particle-selfassembly ability of the full-length HPV 11 L1 protein retained, is easily expressed in an E. coli expression system, and can be economically purified without using expensive enzymes. Furthermore, because the protein of interest is not subjected to the intensive procedures of denaturation and renaturation during purification, the method can be applied industrially on a large scale due to low loss.

The invention will be more apparent after referring to the detailed description and the drawings as follows. All public references are incorporated hereby by reference in their entirety.

DESCRIPTION OF DRAWINGS

FIG. 1 shows the SDS-PAGE result of HPV11N4C-L1 protein during steps a)-d) of the method according to the invention. Lane 1: Lysate supernatant; Lane 2: HPV11N4C-L1 protein precipitated by tengenital flow; Lane 3: Redissolved HPV11N4C-L1 in a re-suspension solution. The result shows that the purity of HPV11N4C-L1 reached about 70% following the steps of precipitation and re-dissolution.

FIG. 2 shows the SDS-PAGE result of HPV11N4C-L1 that was obtained in step d) and was further purified according to step e). Lane 1: HPV11N4C-L1 purified according to step e), 10 μL; Lane 2: HPV11N4C-L1 purified according to step e), 20 μL. The result shows that HPV11N4C-L1 purified according to step e) reached a purity of about 98%.

FIG. 3 shows the transmission electron microscopy (TEM) photograph of HPV11N4C-L1 VLPs obtained in step f), taken at 50,000× magnification. A great deal of VLPs in a radius of about 25 nm were observed in visual field, wherein the particle size was consistant with the theoretic size and the particles were homogenous.

FIG. 4 shows the dynamic light-scattering measurement result of HPV11N4C-L1 VLPs obtained in step f). The result shows that HPV11N4C-L1 VLP had a hydrodynamic radius of 27.19 nm and a particle assembly rate of 96.7%.

FIG. 5 shows titers of neutralizing antibodies in serum at different stages after vaccination of rabbit with HPV11N4C-L1 VLPs. Vaccination times are indicated with arrows. The titer of neutralizing antibodies reached a peak level of 10⁵, 1-2 months after a booster.

FIG. 6 shows the titers of neutralizing antibodies against HPV 6 and HPV11 in serum at different times after vaccination of mice with HPV6/11 bivalent vaccine obtained in Example 5. Vaccine was administered at 0 and 2 weeks. The titers of neutralizing antibodies against HPV6 and HPV 11 increased rapidly after the first vaccination, reaching 10⁴-10⁵.

FIG. 7 shows the titers of neutralizing antibodies against HPV 6, HPV 11, HPV 16 and HPV 18 in serum at different times after vaccination of mice with HPV6/11/16/18 quadrivalent vaccine obtained in Example 5. Vaccine was administered at 0 and 2 weeks. The titers of neutralizing antibodies against HPV 6, HPV 11, HPV 16 and HPV 18 increased rapidly after the first vaccination, reaching 10⁵-10⁶.

FIG. 8 shows the SDS-PAGE results of HPV11N3C-L1, HPV11N5C-L1 and HPV11N6C-L1 protein separately having 3, 5 and 6 amino acids truncated at the N-terminal of HPV 11 L1 protein (the amino acid sequences thereof set forth in SEQ ID Nos: 2, 3 and 4, respectively) during steps a)-e) of the method according to the invention. Lane 1: Molecular Weight Marker; Lane 2: HPV11N3C-L1 purified according to step a)-e), 10 μL; Lane 3: HPV11N5C-L1 purified according to step a)-e), 10 μL; Lane 4: HPV11N6C-L1 purified according to step a)-e), 10 μL. The result shows that the purity of HPV11N3C-L1, HPV11N5C-L1 and HPV11N6C-L1 protein having 3, 5 and 6 amino acids truncated at the N-terminal of HPV 11 L1 protein respectively, reached about 95% following the steps a)-e).

FIG. 9 the transmission electron microscopy (TEM) photographs of the VLPs of HPV11N3C-L1, HPV11N5C-L1 and HPV11N6C-L1 protein separately having 3, 5 and 6 amino acids truncated at the N-terminal of HPV 11 L1 protein obtained following steps a)-f), taken at 50,000× magnification. 1. The transmission electron microscopy (TEM) photographs of HPV11N3C-L1 VLPs obtained following steps a)-f). 2. The transmission electron microscopy (TEM) photographs of HPV11N5C-L1 VLPs obtained following steps a)-f). 3. The transmission electron microscopy (TEM) photographs of HPV11N6C-L1 VLPs obtained following steps a)-f). The results show that a great deal of VLPs in a radius of about 25 nm were observed in visual field, wherein the particle size was consistant with the theoretic size and the particles were homogenous.

FIG. 10 shows the dynamic light-scattering measurement result of the VLPs of HPV11N3C-L1, HPV11N5C-L1 and HPV11N6C-L1 protein separately having 3, 5 and 6 amino acids truncated at the N-terminal of HPV 11 L1 protein obtained following steps a)-f). 1. The dynamic light-scattering measurement result of HPV11N3C-L1 VLPs obtained following steps a)-f). 2. The dynamic light-scattering measurement result of HPV11N5C-L1 VLPs obtained following steps a)-f). 3. The dynamic light-scattering measurement result of HPV11N6C-L1 VLPs obtained following steps a)-f). The result shows that HPV11N3C-L1 VLPs, HPV11N5C-L1 VLPs and HPV11N6C-L1 VLPs had a hydrodynamic radius of about 25 nm and a particle assembly rate of above 80%.

SEQUENCES

SEQ ID NO: 1: 1 MSDSTVYVPP PNPVSKVVAT DAYVKRTNIF YHASSSRLLA VGHPYYSIKK VNKTVVPKVS 61 GYQYRVFKVV LPDPNKFALP DSSLFDPTTQ RLVWACTGLE VGRGQPLGVG VSGHPLLNKY 121 DDVENSGGYG GNPGQDNRVN VGMDYKQTQL CMVGCAPPLG EHWGKGTQCS NTSVQNGDCP 181 PLELITSVIQ DGDMVDTGFG AMNFADLQTN KSDVPLDICG TVCKYPDYLQ MAADPYGDRL 241 FFYLRKEQMF ARHFFNRAGT VGEPVPDDLL VKGGNNRSSV ASSIYVHTPS GSLVSSEAQL 301 FNKPYWLQKA QGHNNGICWG NHLFVTVVDT TRSTNMTLCA SVSKSATYTN SDYKEYMRHV 361 EEFDLQFIFQ LCSITLSAEV MAYIHTMNPS VLEDWNFGLS PPPNGTLEDT YRYVQSQAIT 421 CQKPTPEKEK QDPYKDMSFW EVNLKEKFSS ELDQFPLGRK FLLQSGYRGR TSARTGIKRP 481 AVSKPSTAPK RKRTKTKK SEQ ID NO: 2 1 MPSDSTVYVP PPNPVSKVVA TDAYVKRTNI FYHASSSRLL AVGHPYYSIK KVNKTVVPKV 61 SGYQYRVFKV VLPDPNKFAL PDSSLFDPTT QRLVWACTGL EVGRGQPLGV GVSGHPLLNK 121 YDDVENSGGY GGNPGQDNRV NVGMDYKQTQ LCMVGCAPPL GEHWGKGTQC SNTSVQNGDC 181 PPLELITSVI QDGDMVDTGF GAMNFADLQT NKSDVPLDIC GTVCKYPDYL QMAADPYGDR 241 LFFYLRKEQM FARHFFNRAG TVGEPVPDDL LVKGGNNRSS VASSIYVHTP SGSLVSSEAQ 301 LFNKPYWLQK AQGHNNGICW GNHLFVTVVD TTRSTNMTLC ASVSKSATYT NSDYKEYMRH 361 VEEFDLQFIF QLCSITLSAE VMAYIHTMNP SVLEDWNFGL SPPPNGTLED TYRYVQSQAI 421 TCQKPTPEKE KQDPYKDMSF WEVNLKEKFS SELDQFPLGR KFLLQSGYRG RTSARTGIKR 481 PAVSKPSTAP KRKRTKTKK SEQ ID NO: 3 1 MDSTVYVPPP NPVSKVVATD AYVKRTNIFY HASSSRLLAV GHPYYSIKKV NKTVVPKVSG 61 YQYRVFKVVL PDPNKFALPD SSLFDPTTQR LVWACTGLEV GRGQPLGVGV SGHPLLNKYD 121 DVENSGGYGG NPGQDNRVNV GMDYKQTQLC MVGCAPPLGE HWGKGTQCSN TSVQNGDCPP 181 LELITSVIQD GDMVDTGFGA MNFADLQTNK SDVPLDICGT VCKYPDYLQM AADPYGDRLF 241 FYLRKEQMFA RHFFNRAGTV GEPVPDDLLV KGGNNRSSVA SSIYVHTPSG SLVSSEAQLF 301 NKPYWLQKAQ GHNNGICWGN HLFVTVVDTT RSTNMTLCAS VSKSATYTNS DYKEYMRHVE 361 EFDLQFIFQL CSITLSAEVM AYIHTMNPSV LEDWNFGLSP PPNGTLEDTY RYVQSQAITC 421 QKPTPEKEKQ DPYKDMSFWE VNLKEKFSSE LDQFPLGRKF LLQSGYRGRT SARTGIKRPA 481 VSKPSTAPKR KRTKTKK SEQ ID NO: 4 1 MSTVYVPPPN PVSKVVATDA YVKRTNIFYH ASSSRLLAVG HPYYSIKKVN KTVVPKVSGY 61 QYRVFKVVLP DPNKFALPDS SLFDPTTQRL VWACTGLEVG RGQPLGVGVS GHPLLNKYDD 121 VENSGGYGGN PGQDNRVNVG MDYKQTQLCM VGCAPPLGEH WGKGTQCSNT SVQNGDCPPL 181 ELITSVIQDG DMVDTGFGAM NFADLQTNKS DVPLDICGTV CKYPDYLQMA ADPYGDRLFF 241 YLRKEQMFAR HFFNRAGTVG EPVPDDLLVK GGNNRSSVAS SIYVHTPSGS LVSSEAQLFN 301 KPYWLQKAQG HNNGICWGNH LFVTVVDTTR STNMTLCASV SKSATYTNSD YKEYMRHVEE 361 FDLQFIFQLC SITLSAEVMA YIHTMNPSVL EDWNFGLSPP PNGTLEDTYR YVQSQAITCQ 421 KPTPEKEKQD PYKDMSFWEV NLKEKFSSEL DQFPLGRKFL LQSGYRGRTS ARTGIKRPAV 481 SKPSTAPKRK RTKTKK SEQ ID NO: 5 1 ATGTGGCGGC CTAGCGACAG CACAGTATAT GTGCCTCCTC CCAACCCTGT ATCCAAGGTT 61 GTTGCCACGG ATGCGTATGT TAAACGCACC AACATATTTT ATCACGCCAG CAGTTCTAGA 121 CTCCTTGCTG TGGGACATCC ATATTACTCT ATCAAAAAAG TTAACAAAAC AGTTGTACCA 181 AAGGTGTCTG GATATCAATA TAGAGTGTTT AAGGTAGTGT TGCCAGATCC TAACAAGTTT 241 GCATTACCTG ATTCATCTCT GTTTGACCCC ACTACACAGC GTTTAGTATG GGCGTGCACA 301 GGGTTGGAGG TAGGCAGGGG TCAACCTTTA GGCGTTGGTG TTAGTGGGCA TCCATTGCTA 361 AACAAATATG ATGATGTAGA AAATAGTGGT GGGTATGGTG GTAATCCTGG TCAGGATAAT 421 AGGGTTAATG TAGGTATGGA TTATAAACAA ACCCAGCTAT GTATGGTGGG CTGTGCTCCA 481 CCGTTAGGTG AACATTGGGG TAAGGGTACA CAATGTTCAA ATACCTCTGT ACAAAATGGT 541 GACTGCCCCC CGTTGGAACT TATTACCAGT GTTATACAGG ATGGGGACAT GGTTGATACA 601 GGCTTTGGTG CTATGAATTT TGCAGACTTA CAAACCAATA AATCGGATGT TCCCCTTGAT 661 ATTTGTGGAA CTGTCTGCAA ATATCCTGAT TATTTGCAAA TGGCAGCAGA CCCTTATGGT 721 GATAGGTTGT TTTTTTATTT GCGAAAGGAA CAAATGTTTG CTAGACACTT TTTTAATAGG 781 GCCGGTACTG TGGGGGAACC TGTGCCTGAT GACCTGTTGG TAAAAGGGGG TAATAATAGA 841 TCATCTGTAG CTAGTAGTAT TTATGTACAT ACACCTAGTG GCTCATTGGT GTCTTCAGAG 901 GCTCAATTAT TTAATAAACC ATATTGGCTT CAAAAGGCTC AGGGACATAA CAATGGTATT 961 TGCTGGGGAA ACCACTTGTT TGTTACTGTG GTAGATACCA CACGCAGTAC AAATATGACA 1021 CTATGTGCAT CTGTGTCTAA ATCTGCTACA TACACTAATT CAGATTATAA GGAATACATG 1081 CGCCATGTGG AAGAGTTTGA TTTACAGTTT ATTTTTCAAT TGTGTAGCAT TACATTATCT 1141 GCAGAAGTCA TGGCCTATAT ACACACAATG AATCCTTCTG TTTTGGAGGA CTGGAACTTT 1201 GGTTTATCGC CTCCACCAAA TGGTACACTG GAGGATACTT ATAGATATGT ACAGTCACAG 1261 GCCATTACCT GTCAGAAACC CACACCCGAA AAAGAAAAAC AGGACCCCTA TAAGGATATG 1321 AGTTTTTGGG AGGTTAACTT AAAAGAAAAG TTTTCTTATG AATTAGATCA GTTTCCCCTT 1381 GGACGTAAGT TTTTATTGCA AAGTGGATAT CGAGGACGGA CGTCTGCTCG TACAGGTATA 1441 AAGCGCCCAG CTGTGTCTAA GCCCTCTACA GCCCCCAAAC GAAAACGTAC CAAAACCAGA 1501 AAGTAA SEQ ID NO: 6 1 ATGAGCGACA GCACAGTATA TGTGCCTCCT CCCAACCCTG TATCCAAGGT TGTTGCCACG 61 GATGCGTATG TTAAACGCAC CAACATATTT TATCACGCCA GCAGTTCTAG ACTCCTTGCT 121 GTGGGACATC CATATTACTC TATCAAAAAA GTTAACAAAA CAGTTGTACC AAAGGTGTCT 181 GGATATCAAT ATAGAGTGTT TAAGGTAGTG TTGCCAGATC CTAACAAGTT TGCATTACCT 241 GATTCATCTC TGTTTGACCC CACTACACAG CGTTTAGTAT GGGCGTGCAC AGGGTTGGAG 301 GTAGGCAGGG GTCAACCTTT AGGCGTTGGT GTTAGTGGGC ATCCATTGCT AAACAAATAT 361 GATGATGTAG AAAATAGTGG TGGGTATGGT GGTAATCCTG GTCAGGATAA TAGGGTTAAT 421 GTAGGTATGG ATTATAAACA AACCCAGCTA TGTATGGTGG GCTGTGCTCC ACCGTTAGGT 481 GAACATTGGG GTAAGGGTAC ACAATGTTCA AATACCTCTG TACAAAATGG TGACTGCCCC 541 CCGTTGGAAC TTATTACCAG TGTTATACAG GATGGGGACA TGGTTGATAC AGGCTTTGGT 601 GCTATGAATT TTGCAGACTT ACAAACCAAT AAATCGGATG TTCCCCTTGA TATTTGTGGA 661 ACTGTCTGCA AATATCCTGA TTATTTGCAA ATGGCAGCAG ACCCTTATGG TGATAGGTTG 721 TTTTTTTATT TGCGAAAGGA ACAAATGTTT GCTAGACACT TTTTTAATAG GGCCGGTACT 781 GTGGGGGAAC CTGTGCCTGA TGACCTGTTG GTAAAAGGGG GTAATAATAG ATCATCTGTA 841 GCTAGTAGTA TTTATGTACA TACACCTAGT GGCTCATTGG TGTCTTCAGA GGCTCAATTA 901 TTTAATAAAC CATATTGGCT TCAAAAGGCT CAGGGACATA ACAATGGTAT TTGCTGGGGA 961 AACCACTTGT TTGTTACTGT GGTAGATACC ACACGCAGTA CAAATATGAC ACTATGTGCA 1021 TCTGTGTCTA AATCTGCTAC ATACACTAAT TCAGATTATA AGGAATACAT GCGCCATGTG 1081 GAAGAGTTTG ATTTACAGTT TATTTTTCAA TTGTGTAGCA TTACATTATC TGCAGAAGTC 1141 ATGGCCTATA TACACACAAT GAATCCTTCT GTTTTGGAGG ACTGGAACTT TGGTTTATCG 1201 CCTCCACCAA ATGGTACACT GGAGGATACT TATAGATATG TACAGTCACA GGCCATTACC 1261 TGTCAGAAAC CCACACCCGA AAAAGAAAAA CAGGACCCCT ATAAGGATAT GAGTTTTTGG 1321 GAGGTTAACT TAAAAGAAAA GTTTTCTTAT GAATTAGATC AGTTTCCCCT TGGACGTAAG 1381 TTTTTATTGC AAAGTGGATA TCGAGGACGG ACGTCTGCTC GTACAGGTAT AAAGCGCCCA 1441 GCTGTGTCTA AGCCCTCTAC AGCCCCCAAA CGAAAACGTA CCAAAACCAG AAAGTAA

The description is further illustrated in combination with the Examples, wherein it is not limited to the Examples.

EXAMPLE 1 Expression of the Truncated HPV11 L1 Protein (SEQ ID NO.1)

Preparation of HPV11 L1 Gene Fragments as PCR Template

The full-length gene of HPV-11 L1 was synthesized by Shanghai Boya Bio Co. The synthesized gene fragment has a full length of 1506 by and has a sequence of SEQ ID NO:5. Based on the synthetic full-length gene fragment of HPV-11 L1, the truncated HPV 11 L1 protein according to the invention was prepared as a template.

Construction of Non-Fusion Expression Vector of Truncated HPV11 L1 Gene

The full-length gene fragment of HPV-11 L1 synthesized in the previous step were used as the template for the next PCR reaction. The forward primer was 11N4F: 5′-CAT ATG AGC GAC AGC ACA GTA TAT GTG-3′ (SEQ ID NO: 10), at the 5′ terminal of which the restriction endonuclease NdeI site was introduced. The sequence of NdeI site was CAT ATG, wherein ATG was the initiation codon in E. coli system. The reverse primer was 6CR: 5′-GTC GAC TTA CTT TCT GGT TTT GGT ACG TTT-3′ (SEQ ID NO: 11), at the 5′ terminal of which the restriction endonuclease SalI site was introduced. Amplification was performed in a Biometra T3 PCR thermocycler using the following parameters:

94° C. denaturation 5 min  1 cycle 94° C. denaturation 50 sec 25 cycles 57° C. annealing 50 sec 72° C. elongation 2 min 72° C. elongation 10 min  1 cycle

The DNA fragments, about 1.5 kb in length, were obtained after amplification. The PCR products were linked to the pMD 18-T vector (Takara Biosciences). After digestion with NdeI/SalI, it was identified that positive colonies, wherein the truncated HPV11 L1 gene was inserted, were obtained, designated as pMD 18-T-HPV11N4C-L1.

The nucleotide sequence of interest, which was inserted into the plasmid pMD 18-T-HPV11N4C-L1, was determined as SEQ ID NO: 6 by Shanghai Boya Bio Co. through using M13+/− primers. SEQ ID NO:6 encodes the amino acid sequence set forth in SEQ ID NO:1 which corresponds to a HPV 11 L1 protein having 4 amino acids truncated at its N-terminal and no amino acid truncated at its C-terminal and was designated as HPV11N4C-L1.

The truncated HPV11N4C-L1 gene fragments were obtained by NdeI/SalI digestion of plasmid pMD 18-T-HPV11N4C-L1. The fragments were linked to Non-Fusion Expression Vector pTO-T7 (Luo Wenxin et al., Chinese Journal of Biotechnology, 2000, 16:53-57). Colonies were screened with NdeI/SalI digestion. Positive colonies containing the insert of the L1 gene fragment were labeled pTO-T7-HPV11N4C-L1. 1 μL plasmid pTO-T7-HPV11N4C-L1 (0.15 mg/ml) was used to transform 40 μL competent E. coli ER2566 (New England Labs) prepared by Calcium chloride method, and then was coated on solid LB medium containing kanmycin (at a final concentration of 25 mg/mL, the same as below). The plates were incubated at 37° C. for about 10-12 h until single colonies could be observed clearly. Single colonies were transferred to a tube containing 4 ml liquid LB medium containing kanmycin. Cultures were incubated in a shaking incubator at 220 rpm for 10 h at 37° C., and then 1 ml bacterial solution was freeze-dried and stored at −70° C.

Expression of HPV11N4C-L1 in Large Scale

E. coli transformed with pTO-T7-HPV11N4C-L1 was taken from the freeze-dried strain at −70° C. and diluted with a little sterile water, and then incubated in 50 mL LB medium containing Kanamycin at 200 rpm and 37° C. for 8 h. Then, the cultures were transferred to ten flasks (5 ml culture per flask), each of which contains 500 mL LB medium, and were incubated in a shaking incubator overnight at 200 rpm and 30° C. The cultures were the starter cultures.

-   -   LB medium:     -   Peptone: 10 g     -   Yeast extract: 5 g     -   NaCl: 10 g

The above components were dissolved in 1 L deionized water; the resultant solution was adjusted to pH 7.2 by addition of NaOH, sterilized at 121° C. for 30 minutes and cooled to 50° C.

A 50 L fermenter made by Shanghai Baoxing Biological Ltd was used in large-scale incubation. pH electrode was calibrated. 30 L LB medium was prepared and transferred into the fermenter, sterilized in situ at 121° C. for 30 minutes. Dissolved oxygen electrode was calibrated, wherein the value was determined as 0 before introduction of air after sterilization and as 100% prior to vaccination after introduction of air while stirring at 100 rpm at the beginning.

Preparation of the feed: 20 g peptone and 10 g yeast extract were dissolved in 100 ml deionized water to prepare a mixture of peptone and yeast extract (30%), and 50 g glucose was dissolved in 100 ml deionized water to prepared a glucose solution (50%). The two mixtures were sterilized at 121° C. for 20 min.

On the second day, the starter cultures in the ten flasks (for a total of 5 L) were transferred to the fermenter. At 37° C. and pH 7.0, the dissolved O₂ was maintained at >40% by regulating agitation rate or air supply manually.

Flow Feed: 50% glucose and 30% mixture of peptone and yeast extract were mixed at a 2:1 mass ratio.

Flow rates were as follows:

25 mL/min was defined as 100%.

1 h: 5%

2 h: 10%

3 h: 20%

4 h: 40%

5 h to the end: 60%

When OD_(600nm) reached about 10, the culture temperature was lowered to 25° C. and 4 g IPTG was added to begin induction culture of 4 h. Fermentation was halted when OD_(600nm) reached about 60. The culture was then centrifuged to obtain target strains expressing the HPV11N4C-L1 protein (about 2.7 kg).

EXAMPLE 2 Preparation HPV11N4C-L1 with a purity of about 70%

1 g strains were re-suspended in 10 ml lysis buffer (20 mM tris buffer pH 7.2, 300 mM NaCl). Strains were disrupted by passing through a APV homogenizer (Invensys Group) for five times at a pressure of 600 bar. The homogenate was centrifuged at 30,000 g (13,500 rpm in JA-14 rotor) for 15 min. The supernatant was subjected to SDS-PAGE on a 10% gel. At this stage, the HPV11N4C-L1 had a purity of about 10%. The supernatant was dialyzed by a Centrasette 5 Tangential Flow Filter (Pall Co.) running at a pressure of 0.5 psi, a flow rate of 500 ml/min, and a tangential flow rate of 200 mL/min, wherein the retention molecular weight was 30 kDa, the dialysate was 10 mM phosphate buffer pH 6.0, and the dialysis volume was three times as large as the volume of supernatant. After thorough dialysis, the mixture was centrifuged at 12,000 g (9500 rpm in JA-10 rotor (Beckman J25 high speed centrifuge)) for 20 min, and the precipitation was collected. The precipitation was re-suspended in 10 mM phosphate buffer pH 8.0 containing 10 mM DTT and 300 mM NaCl, wherein the volume of the buffer was 1/10 times as large as the volume of the supernatant. The mixture was stirred for 30 min and centrifuged at 30,000 g (13,500 rpm in JA-14 rotor (Beckman J25 high speed centrifuge)) for 20 min. The supernatant passes through a 0.22 μm filter membrane. The sample was further subjected to cation exchange chromatography. 30 μL of 6× loading buffer was added to 150 μL of the filtered supernatant, and the result solution was mixed. After heating in a water bath at 80° C. for 10 min, a 10 uL sample was subjected to SDS-PAGE on a 10% gel at 120V for 120 min. The electrophoretic bands were stained by Coomassie brilliant blue. The result was shown in FIG. 1. According to the analysis of SDS-PAGE, HPV11N4C-L1 protein was purified and enriched after the steps of precipitation and re-dissolution, with the purity increased to about 70%.

EXAMPLE 3 Chromatography Purification of HPV11N4C-L1

Cation Exchange Chromatography of HPV11N4C-L1

Equipment: AKTA Explorer 100 preparative liquid chromatography system (GE Healthcare, i.e. the original Amershan Pharmacia Co.)

Chromatographic media: SP Sepharose 4 Fast Flow

Column Volume: 5.5 cm×20 cm

Buffer: 20 mM phosphate buffer pH 8.0, 10 mM DTT

20 mM phosphate buffer pH 8.0, 10 mM DTT, 2M NaCl

Flow Rate: 25 mL/min

Detector Wavelength: 280 nm

Sample: 3 L, about 70% HPV11N4C-L1 solution

Elution protocol: eluting undesired proteins with 200 mM NaCl, eluting the protein of interest with 800 mM NaCl, collecting 500 mM NaCl elutate, and finally getting about 700 mL purified HPV11N4C-L1 sample.

Purification of HPV11N4C-L1 by CHT-II Chromatography

Equipment: AKTA Explorer 100 preparative liquid chromatography system (GE Healthcare, i.e. the original Amershan Pharmacia Co.)

Chromatographic media: CHT-II (Bio-Rad)

Column Volume: 5.5 cm×20 cm

Buffer: 10 mM phosphate buffer pH7.0, 10 mM DTT, 0.5M NaCl

Flow Rate: 20 mL/min

Detector Wavelength: 280 nm

Sample: 500 mM NaCl elutate from SP Sepharose 4 Fast Flow

Elution protocol: directly collecting the pass-through containing the protein of interest.

The pass-through, which contains HPV11N4C-L1, was collected and about 300 mL purified HPV11N4C-L1 was obtained. 30 μL 6× loading buffer was added to 150 μL HPV11N4C-L1 sample purified according to the method of the Example, and then the result solution was mixed thoroughly. After heating the solution in a water bath at 80° C. for 10 min, a 10 uL sample was subjected to SDS-PAGE on a 10% gel at 120V for 120 min. The electrophoretic bands were stained by Coomassie brilliant blue. The result was shown in FIG. 2. The concentration of the protein of interest was about 0.3 mg/ml, and the purity was greater than 98% according to SDS-PAGE.

EXAMPLE 4 Assembly of HPV11N4C-L1 VLPs

Equipment: Centrasette 5 Tangential Flow Filter (Pall Co.), retention MW 30 kDa.

Sample: 300 mL HPV11N4C-L1 obtained in Example 3

Sample Concentration Sample was concentrated to 800 mL with the system tangential flow rate adjusted to 50 mL/min

Sample Renaturation: Sample buffer was exchanged with 10 L renaturation buffer (20 mM PB pH 6.0, 2 mM CaCl₂, 2 mM MgCl₂, 0.5M NaCl, 0.003% Tween-80) thoroughly. When running the Tangential Flow Filter, the pressure was 0.5 psi and the tangential flow rate was 10 mL/min. When exchange was finished, the sample buffer was replaced with storage buffer (20 L PBS: 20 mM PB pH 6.5, 0.5M NaCl). The exchange volume was 20 L. The running pressure was 0.5 psi and the tangential flow rate was 25 mL/min. When the liquid exchange was finished, the sample was aseptically filtrated with a Pall filter (0.20 μm). The HPV11N4C-L1 VLPs were obtained and were stored at for further use.

EXAMPLE 5 Determination of the Morphology of HPV11N4C-L1 VLPs

Transmission Electron Microscopy (TEM) of HPV11N4C-L1 VLPs

The equipment was a JEOL 100 kV Transmission Electron Microscope (100,000× magnification). HPV11N4C-L1 VLPs were negatively stained with 2% phosphotungstic acid at pH 7.0, and fixed on a copper grid. Results were shown in FIG. 3. It could be seen that the VLPs obtained in Example 4 had a radius of approximately 25 nm, and were homogenous and in a hollow form.

Dynamic Light-Scattering Measurement of HPV11N4C-L1 VLPs

DynaPro MS/X dynamic light-scattering instrument (including a temperature controller) (US Protein Solutions Co.) was used for light-scattering measurements. The regulation algorithm was used in the measurements. The sample was the one obtained in Example 4. The sample was passed through a 0.22 μm filter membrane prior to the measurement. Results were shown in FIG. 4. The result shows that HPV11N4C-L1 VLPs had a Hydrodynamic radius of 27.19 nm and a particle assembly rate of 96.7%.

Establishment of Pseudovirion Neutralization Assay for HPV11

HPV can hardly be cultured in vitro, and the HPV host had a strong specificity. Thus, HPV can hardly be propagated in hosts other than human. That is, there was not an appropriate animal model for HPV. Therefore, in order to evaluate the immune productivity of HPV vaccine quickly, there was a need to establish a efficient model for in vitro neutralization assays.

In Vitro Infection Model of Pseudovirion: According to the characteristic that HPV VLP can package nucleic acids non-specifically, HPV pseudivirion was formed by expressing HPV L1 and L2 protein in cells, and by packaging viral DNA of episome or introducing reporter plasmids heterologously. Methods include expression systems based on recombinant viruses and cotransfection of multi-plasmids (see Yeager, M. D, Aste-Amezaga, M. et al (2000) Virology (278) 570-7).

The invention utilizes cotransfection of a multi-plasmid system. Some improvements were made as follows. An optimized calcium phosphate transfection method was established for the 293FT cell line, with a transfection efficiency of above 90%, which facilitate the production on a large scale. The resultant codon-optimized expression plasmid of HPV structural protein could express HPV L1 and L2 gene efficiently in mammalian cell lines, facilitating efficient assembly of pseudovirion.

Construction of HPV Pseudovirion:

P11L1h, p11L2h and pN31-EGFP (donated by Professor John T. Schiller of NIH) contain genes for HPV11L1, HPV11L2, and GFP, respectively. These plasmids were purified using CsCl density gradient centrifugation as described in The Molecular Cloning Experiment Guide, (3rd edition). The purification procedure was as follows:

-   -   Plasmids were used to transform E. coli DH5α;     -   Single colonies were transferred into 500 mL LB culture medium         and incubated in a shaking flask at 37° C. for 16 h;     -   Culture medium was centrifuged at 9,000 g for 5 min and the         stains were collected;     -   The following substances were successively added to bacteria in         each 1000 mL LB: 40 mL solution I (50 mM glucose, 25 mM Tris-Cl         pH 8.0, 10 mM EDTA pH 8.0) and 2 ml 1 μg/μL RNase A), 40 mL         solution II (0.2M NaOH, 1% SDS), and 48 mL solution III (60.0 mL         5M potassium acetate, 11.5 mL acetic acid, and 28.5 mL deionized         water);     -   After placing on ice for 10 min, the mixture was centrifuged at         15,000 g for 20 min at 4° C.;     -   The supernatant was mixed with 0.6 volume of isopropyl alcohol,         then was centrifuged again at 15,000 g for 30 min at 4° C.;     -   The supernatant was decanted into waste and the precipitation         was washed with 70% ethanol;     -   The precipitation was dissolved in TE and the content of DNA was         determined;     -   CsCl was dissolved in the solution of DNA (1 g DNA per 1.01 g         CsCl), and then 100 μL 10 mg/mL EB solution was also dissolved         in it;     -   The mixture was centrifuged using a Beckman NVT65 centrifuge at         62,000 rpm for 10 hr at 20° C.;     -   Closed circle DNA section was collected using an injector         pinhead;     -   EB was extracted with equivalent volume of Isoamyl alcohol         repeatedly for four times;     -   Three volumes of deionized water and eight volumes of dry         ethanol were added to one volume of DNA solution, and then the         mixture was centrifuged at 20000 g for 30 min at 4° C.;     -   The DNA precipitation was collected and washed with 75% ethanol,         and then dissolved in 1 mL TE;     -   The concentration of the DNA solution was determined, then the         solution was stored in small packages at −20° C.

The purified p11L1h, p11L2h and pN31-EGFP co-transfected 293FT cells (Invitrogen) cultured on a 10 cm cell culture plate by calcium phosphate method. The calcium phosphate method was described as follows. 40 μg p11L1h, 40 μg p11L2h, and 40 μg pN31-EGFP were separately added to the mixture of 1 mL HEPES solution (125 μL 1M HEPES/50 mL deionized water, at pH7.3 and 4° C.) and 1 mL 0.5M CaCl₂ solution. After mixing, 2 mL 2× HeBS solution (0.28M NaCl (16.36 g), 0.05M HEPES (11.9 g), 1.5 mM Na₂HPO₄ (0.213 g), dissolved in 1000 mL deionized water, at pH 6.96 and −70° C.) was added dropwise. After standing at room temperature for 1 min, the mixture was added to the 10 cm cell culture plate where the 293FT cells were cultured. The original culture medium was replaced with 10 ml complete medium (Invitrogen Co.) 6 hours later. 48 hours after transfection, the medium was decanted and the cells were washed twice with PBS. Then, the cells were collected and counted. Every 10⁸ cells were suspended in 1 mL cytolytic solution (0.25% Brij58, 9.5 mM MgCl₂). After lysing, cell lysate was centrifugated at 5,000 g for 10 min and the supernatant was collected. The Pseudovirion solution was obtained after adding 5M NaCl to the supernatant to a final concentration of 850 mM, then was stored in small packages at −20° C.

293FT cells (Invitrogen) were spread on a 96-well cell culture plate (1.5×10⁴ cells/well). Neutralization assay was performed five hours later. Serum samples were serially diluted with 10% DMEM half-by-half 50 μL diluted samples were separately mixed with 50 μL Pseudovirion solutions diluted with 10% DMEM (moi=0.1). After incubating at 4° C. for 1 h, the mixture was added to the 96-well cell culture plate spread with 293FT cells. The mixture was then incubated for 72 h at 37° C. Neutralization titers of samples were estimated by observing fluorescence. Infection percentage of cells in each well was checked by flow cytometry (EPICS XL, American Beckman Coulter Co.). The exact titers of monoclonal antibodies or polyclonal antibodies were calculated. Infection percentage was the percentage of cells in the positive region minus the uninfected cells in the positive region. Infection control percentage=(1−infection percentage of sample cell/infection percentage of negative cell)×100%

Neutralization titer was defined as the highest dilution multiple by which the infection control percentage was just above 50%. Monoclonal and polyclonal antibodies were considered as having neutralizing capacity if their infection control percentage was above 50% after 50 times dilutions.

Measurement of Immune Protection of Animals Vaccinated with HPV11 VLPs:

Female rabbits (general level), 6-8 weeks old, were purchased from the Disease Prevention and Control Center of Guangxi province, where they were raised. HPV11N4C-L1 VLPs prepared in Example 4, were mixed with equal amount of complete Freund's Adjuvant for the first immunization. For the booster, HPV11N4C-L1 VLPs were mixed with incomplete Freund's Adjuvant. Rabbits were immunized via muscle injection, with 100 μg per rabbit for the first immunization, and with 50 μg per rabbit for the booster separately at week 4, 10. After immunization, external vein blood was collected every week, and serum was separated and stored for detection.

Neutralization titers of the anti-serums were evaluated using a pseudovirion-based neutralization cell model assay. As shown in FIG. 5, the vaccine produced by mixing HPV11N4C-L1 VLPs prepared in Example 4, could induce neutralizing antibodies with a high titer in animals, and could be used as an effective vaccine for the prevention of HPV infection.

Measurement of Immune Protection of Rhesus Monkeys Vaccinated with HPV6/11 Bivalent Vaccine

Four SPF BALB/c mice, 4-5 weeks old, were used. HPV6N5C-L1 VLPs and HPV11N4C-L1 VLPs, which were prepared according to the method similar to that of Examples 1-4, were mixed at a ratio of 1:2 (by weight), wherein the final concentrations of them were 40 μg/mL and 80 μg/mL, respectively. The vaccine was mixed with an equal amount of complete Freund's adjuvant for the first immunization, and was mixed with an equal amount of incomplete Freund's adjuvant for the booster.

Mice were immunized by muscle injection. The amount for the first immunization was 10 μg HPV6N5C-L1 and 20 μg HPV11N4C-L1 per mouse. The booster was administered every two weeks. The amount for the booster was 2 μg HPV6N5C-L1 and 40 μg HPV11N4C-L1 per mouse.

After immunization, external vein blood was collected every week and serum was separated. The titers of neutralizing antibodies against HPV6 and HPV11 in immunized mice were separately determined according to the method of Example 5.

Results were shown in FIG. 6, indicating that HPV6/11 bivalent vaccine, prepared by blending HPV6N5C-L1 and HPV11N4C-L1 VLPs prepared according to the method as described in Examples 1-4, had good immunogenicity, could induce neutralizing antibodies with a high titer against HPV 6 and HPV 11 in animals, and could be used as an effective vaccine for the prevention of HPV6/HPV11 infection (besides the Freund's adjuvants used in the experiments, the vaccine may be prepared by blending the two VLPs of HPV16N5C-L1 and HPV11N4C-L1 with aluminum hydroxide or aluminum phosphate adjuvants available commercially or self-prepared).

The Amino Acid Sequence of L1 of HPV6N5C-L1 is showed in SEQ ID NO: 7 as follows.

Met Asp Ser Thr Val Tyr Val Pro Pro Pro Asn Pro Val Ser Lys Val 1                5                      10                   15 Val Ala Thr Asp Ala Tyr Val Thr Arg Thr Asn Ile Phe Tyr His Ala              20                     25                     30 Ser Ser Ser Arg Leu Leu Ala Val Gly His Pro Tyr Phe Ser Ile Lys         35                    40                     45 Arg Ala Asn Lys Thr Val Val Pro Lys Val Ser Gly Tyr Gln Tyr Arg     50                     55                    60 Val Phe Lys Val Val Leu Pro Asp Pro Asn Lys Phe Ala Leu Pro Asp 65                   70                    75                   80 Ser Ser Leu Phe Asp Pro Thr Thr Gln Arg Leu Val Trp Ala Cys Thr                  85                   90                     95 Gly Leu Glu Val Gly Arg Gly Gln Pro Leu Gly Val Gly Val Ser Gly              100                    105                   110 His Pro Phe Leu Asn Lys Tyr Asp Asp Val Glu Asn Ser Gly Ser Gly          115                  120                   125 Gly Asn Pro Gly Gln Asp Asn Arg Val Asn Val Gly Met Asp Tyr Lys     130                  135                   140 Gln Thr Gln Leu Cys Met Val Gly Cys Ala Pro Pro Leu Gly Glu His 145                  150                    155                 160 Trp Gly Lys Gly Lys Gln Cys Thr Asn Thr Pro Val Gln Ala Gly Asp                   165                   170                   175 Cys Pro Pro Leu Glu Leu Ile Thr Ser Val Ile Gln Asp Gly Asp Met             180                     185                    190 Val Asp Thr Gly Phe Gly Ala Met Asn Phe Ala Asp Leu Gln Thr Asn         195                    200                   205 Lys Ser Asp Val Pro Ile Asp Ile Cys Gly Thr Thr Cys Lys Tyr Pro     210                     215                   220 Asp Tyr Leu Gln Met Ala Ala Asp Pro Tyr Gly Asp Arg Leu Phe Phe 225                   230                   235                 240 Phe Leu Arg Lys Glu Gln Met Phe Ala Arg His Phe Phe Asn Arg Ala                 245                   250                   255 Gly Glu Val Gly Glu Pro Val Pro Asp Thr Leu Ile Ile Lys Gly Ser             260                   265                     270 Gly Asn Arg Thr Ser Val Gly Ser Ser Ile Tyr Val Asn Thr Pro Ser         275                    280                     285 Gly Ser Leu Val Ser Ser Glu Ala Gln Leu Phe Asn Lys Pro Tyr Trp     290                    295                  300 Leu Gln Lys Ala Gln Gly His Asn Asn Gly Ile Cys Trp Gly Asn Gln 305                   310                    315                320 Leu Phe Val Thr Val Val Asp Thr Thr Arg Ser Thr Asn Met Thr Leu                  325                    330                  335 Cys Ala Ser Val Thr Thr Ser Ser Thr Tyr Thr Asn Ser Asp Tyr Lys              340                    345                   350 Glu Tyr Met Arg His Val Glu Glu Tyr Asp Leu Gln Phe Ile Phe Gln         355                    360                   365 Leu Cys Ser Ile Thr Leu Ser Ala Glu Val Val Ala Tyr Ile His Thr     370                    375                    380 Met Asn Pro Ser Val Leu Glu Asp Trp Asn Phe Gly Leu Ser Pro Pro 385                   390                  395                   400 Pro Asn Gly Thr Leu Glu Asp Thr Tyr Arg Tyr Val Gln Ser Gln Ala                    405                  410                   415 Ile Thr Cys Gln Lys Pro Thr Pro Glu Lys Gln Lys Pro Asp Pro Tyr               420                   425                   430 Lys Asn Leu Ser Phe Trp Glu Val Asn Leu Lys Glu Lys Phe Ser Ser         435                   440                   445 Glu Leu Asp Gln Tyr Pro Leu Gly Arg Lys Phe Leu Leu Gln Ser Gly     450                   455                   460 Tyr Arg Gly Arg Ser Ser Ile Arg Thr Gly Val Lys Arg Pro Ala Val 465                    470                    475               480 Ser Lys Ala Ser Ala Ala Pro Lys Arg Lys Arg Ala Lys Thr Lys Arg                   485                   490                    495

Measurement of Immune protection of mice vaccinated with HPV6/11/16/18 Quadrivalent Vaccine

Four SPF BALB/c mice, 4-5 weeks old, were used. HPV6N5C-L1, HPV11N4C-L1, HPV16N30C-L1 and HPV18N65C-L1 VLPs, prepared according to the method similar to that of Examples 1-4, were mixed at a ratio of 1:2:2:1 (by weight), wherein the final concentrations of them were 40 μg/mL, 80 μg/mL, 80 μg/mL and 40 μg/mL, respectively. The vaccine was mixed with an equal amount of complete Freund's adjuvant for the first immunization, and was mixed with an equal amount of incomplete Freund's adjuvant for the booster.

Mice were immunized by muscle injection. The amount for the first immunization was 10 μg HPV6N5C-L1, 10 μg HPV18N65C-L1, 20 μg HPV11N4C-L1, and 20 μg HPV16N30C-L1 per mouse. The booster was administered every two weeks. The amount for the booster was 20 μg HPV6N5C-L1, 20 μg HPV18N65C-L1, 40 μg HPV11N4C-L1, and 40 μg HPV16N30C-L1 per mouse.

After immunization, external vein blood was collected every week and serum was separated. The titers of neutralizing antibodies against HPV6, HPV11, HPV16 and HPV 18 in immunized mice were separately determined according to the method of Example 5.

Results were shown in FIG. 7, indicating that HPV6/11/16/18 quadrivalent vaccine, prepared by blending HPV6N5C-L1, HPV11N4C-L1, HPV16N30C-L1 and HPV18N65C-L1 VLPs prepared according to the method as described in Examples 1-4, had good immunogenicity, could induce neutralizing antibodies with a high titer against HPV 6, HPV 11, HPV 16, and HPV 18 in animals, and could be used as a effective vaccine for the prevention of HPV6/HPV11/HPV16/HPV18 infection (besides the Freund's adjuvants used in the experiments, the vaccine may be prepared by blending the four VLPs of HPV6N5C-L1, HPV11N4C-L1, HPV16N30C-L1 and HPV18N65C-L1 VLPs with aluminum hydroxide or aluminum phosphate adjuvants available commercially or self-prepared).

The Amino Acid Sequence of L1 of HPV16N30C-L1 is showed in SEQ ID NO 8 as follows.

Met Leu Pro Ser Glu Ala Thr Val Tyr Leu Pro Pro Val Pro Val Ser 1                5                     10                    15 Lys Val Val Ser Thr Asp Glu Tyr Val Ala Arg Thr Asn Ile Tyr Tyr              20                     25                     30 His Ala Gly Thr Ser Arg Leu Leu Ala Val Gly His Pro Tyr Phe Pro          35                    40                     45 Ile Lys Lys Pro Asn Asn Asn Lys Ile Leu Val Pro Lys Val Ser Gly      50                   55                     60 Leu Gln Tyr Arg Val Phe Arg Ile His Leu Pro Asp Pro Asn Lys Phe 65                    70                     75                80 Gly Phe Pro Asp Thr Ser Phe Tyr Asn Pro Asp Thr Gln Arg Leu Val                  85                   90                    95 Trp Ala Cys Val Gly Val Glu Val Gly Arg Gly Gln Pro Leu Gly Val              100                    105                   110 Gly Ile Ser Gly His Pro Leu Leu Asn Lys Leu Asp Asp Thr Glu Asn           115                   120                  125 Ala Ser Ala Tyr Ala Ala Asn Ala Gly Val Asp Asn Arg Glu Cys Ile      130                    135                  140 Ser Met Asp Tyr Lys Gln Thr Gln Leu Cys Leu Ile Gly Cys Lys Pro 145                   150                 155                160 Pro Ile Gly Glu His Trp Gly Lys Gly Ser Pro Cys Thr Asn Val Ala                    165                   170                   175 Val Asn Pro Gly Asp Cys Pro Pro Leu Glu Leu Ile Asn Thr Val Ile              180                  185                    190 Gln Asp Gly Asp Met Val Asp Thr Gly Phe Gly Ala Met Asp Phe Thr         195                   200                   205 Thr Leu Gln Ala Asn Lys Ser Glu Val Pro Leu Asp Ile Cys Thr Ser     210                   215                   220 Ile Cys Lys Tyr Pro Asp Tyr Ile Lys Met Val Ser Glu Pro Tyr Gly 225                 230                   235                  240 Asp Ser Leu Phe Phe Tyr Leu Arg Arg Glu Gln Met Phe Val Arg His                 245                   250                   255 Leu Phe Asn Arg Ala Gly Ala Val Gly Asp Asn Val Pro Asp Asp Leu             260                   265                  270 Tyr Ile Lys Gly Ser Gly Ser Thr Ala Asn Leu Ala Ser Ser Asn Tyr           275                    280                  285 Phe Pro Thr Pro Ser Gly Ser Met Val Thr Ser Asp Ala Gln Ile Phe     290                   295                   300 Asn Lys Pro Tyr Trp Leu Gln Arg Ala Gln Gly His Asn Asn Gly Ile 305                   310                   315               320 Cys Trp Gly Asn Gln Leu Phe Val Thr Val Val Asp Thr Thr Arg Ser                  325                  330                    335 Thr Asn Met Ser Leu Cys Ala Ala Ile Ser Thr Ser Glu Thr Thr Tyr             340                    345                   350 Lys Asn Thr Asn Phe Lys Glu Tyr Leu Arg His Gly Glu Glu Tyr Asp         355                   360                   365 Leu Gln Phe Ile Phe Gln Leu Cys Lys Ile Thr Leu Thr Ala Asp Ile     370                   375                    380 Met Thr Tyr Ile His Ser Met Asn Ser Thr Ile Leu Glu Asp Trp Asn 385                     390                   395              400 Phe Gly Leu Gln Pro Pro Pro Gly Gly Thr Leu Glu Asp Thr Tyr Arg                  405                   410                   415 Phe Val Thr Ser Gln Ala Ile Ala Cys Gln Lys His Thr Pro Pro Ala              420                    425                  430 Pro Lys Glu Asp Pro Leu Lys Lys Tyr Thr Phe Trp Glu Val Asn Leu          435                  440                   445 Lys Glu Lys Phe Ser Ala Asp Leu Asp Gln Phe Pro Leu Gly Arg Lys     450                   455                  460 Phe Leu Leu Gln Ala Gly Leu Glu Ala Lys Pro Lys Phe Thr Leu Gly 465                   470                   475                480 Lys Arg Lys Ala Thr Pro Thr Thr Ser Ser Thr Ser Thr Thr Ala Lys                   485                   490                   495 Arg Lys Lys Arg Lys Leu              500

The Amino Acid Sequence of L1 of HPV18N65C-L1 is showed in SEQ ID NO 9 as follows.

Met Arg Pro Ser Asp Asn Thr Val Tyr Leu Pro Pro Pro Ser Val Ala 1                5                    10                     15 Arg Val Val Asn Thr Asp Asp Tyr Val Thr Arg Thr Ser Ile Phe Tyr              20                    25                     30 His Ala Gly Ser Ser Arg Leu Leu Thr Val Gly Asn Pro Tyr Phe Arg          35                  40                     45 Val Pro Ala Gly Gly Gly Asn Lys Gln Asp Ile Pro Lys Val Ser Ala      50                   55                     60 Tyr Gln Tyr Arg Val Phe Arg Val Gln Leu Pro Asp Pro Asn Lys Phe 65                    70                    75                 80 Gly Leu Pro Asp Thr Ser Ile Tyr Asn Pro Glu Thr Gln Arg Leu Val                  85                     90                   95 Trp Ala Cys Ala Gly Val Glu Ile Gly Arg Gly Gln Pro Leu Gly Val              100                    105                    110 Gly Leu Ser Gly His Pro Phe Tyr Asn Lys Leu Asp Asp Thr Glu Ser         115                    120                 125 Ser His Ala Ala Thr Ser Asn Val Ser Glu Asp Val Arg Asp Asn Val     130                    135                   140 Ser Val Asp Tyr Lys Gln Thr Gln Leu Cys Ile Leu Gly Cys Ala Pro 145                   150                   155                160 Ala Ile Gly Glu His Trp Ala Lys Gly Thr Ala Cys Lys Ser Arg Pro                    165                   170                  175 Leu Ser Gln Gly Asp Cys Pro Pro Leu Glu Leu Lys Asn Thr Val Leu             180                   185                  190 Glu Asp Gly Asp Met Val Asp Thr Gly Tyr Gly Ala Met Asp Phe Ser         195                   200                    205 Thr Leu Gln Asp Thr Lys Cys Glu Val Pro Leu Asp Ile Cys Gln Ser     210                   215                   220 Ile Cys Lys Tyr Pro Asp Tyr Leu Gln Met Ser Ala Asp Pro Tyr Gly 225                    230                   235               240 Asp Ser Met Phe Phe Cys Leu Arg Arg Glu Gln Leu Phe Ala Arg His                 245                 250                   255 Phe Trp Asn Arg Ala Gly Thr Met Gly Asp Thr Val Pro Gln Ser Leu             260                    265                   270 Tyr Ile Lys Gly Thr Gly Met Arg Ala Ser Pro Gly Ser Cys Val Tyr           275                   280                   285 Ser Pro Ser Pro Ser Gly Ser Ile Val Thr Ser Asp Ser Gln Leu Phe     290                    295                   300 Asn Lys Pro Tyr Trp Leu His Lys Ala Gln Gly His Asn Asn Gly Val 305                   310                   315                320 Cys Trp His Asn Gln Leu Phe Val Thr Val Val Asp Thr Thr Arg Ser                  325                   330                   335 Thr Asn Leu Thr Ile Cys Ala Ser Thr Gln Ser Pro Val Pro Gly Gln             340                     345                   350 Tyr Asp Ala Thr Lys Phe Lys Gln Tyr Ser Arg His Val Glu Glu Tyr         355                   360                   365 Asp Leu Gln Phe Ile Phe Gln Leu Cys Thr Ile Thr Leu Thr Ala Asp     370                   375                   380 Val Met Ser Tyr Ile His Ser Met Asn Ser Ser Ile Leu Glu Asp Trp 385                     390                   395              400 Asn Phe Gly Val Pro Pro Pro Pro Thr Thr Ser Leu Val Asp Thr Tyr                  405                   410                   415 Arg Phe Val Gln Ser Val Ala Ile Ala Cys Gln Lys Asp Ala Ala Pro              420                    425                   430 Ala Glu Asn Lys Asp Pro Tyr Asp Lys Leu Lys Phe Trp Asn Val Asp          435                  440                   445 Leu Lys Glu Lys Phe Ser Leu Asp Leu Asp Gln Tyr Pro Leu Gly Arg     450                   455                   460 Lys Phe Leu Val Gln Ala Gly Leu Arg Arg Lys Pro Thr Ile Gly Pro 465                   470                   475                480 Arg Lys Arg Ser Ala Pro Ser Ala Thr Thr Ala Ser Lys Pro Ala Lys                   485                   490                   495 Arg Val Arg Val Arg Ala Arg Lys              500

The Amino Acid Sequence of L1 of HPV6N5C-L1 VLP is shown in SEQ ID NO:7, as described above.

EXAMPLE 6

The truncated HPV11L1 proteins set forth in SEQ ID NOs: 2, 3 and 4 were prepared according to the techniques used in examples 1-5. All these truncated proteins could be purified to an extent of above 98% and could be assembled into VLPs with a radius of about 25 nm. The results are shown in FIGS. 8, 9 and 10. 

The invention claimed is:
 1. A vaccine for prevention of condyloma acuminatum or HPV infections, comprising vaccine A or vaccine B: wherein the vaccine A comprises: (A1) HPV11 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 1; (A2) HPV6 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 7; and (A3) carriers or excipients useful for vaccines; and wherein the vaccine B comprises: (B1) HPV11 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 1; (B2) HPV6 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 7; (B3) HPV16 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 8; (B4) HPV18 VLP comprising a protein consisting of the amino acid sequence set forth in SEQ ID NO: 9; and (B5) carriers or excipients useful for vaccines.
 2. The vaccine as claimed in claim 1, wherein the vaccine comprises the HPV6 VLP and the HPV11 VLP.
 3. The vaccine as claimed in claim 2, wherein the vaccine comprises a combination of the HPV6 VLP, the HPV11 VLP, the HPV 16 VLP and the HPV 18 VLP.
 4. A method for preventing condyloma acuminatum or HPV infections, comprising administering a vaccine comprising a preventively effective amount of the vaccine according to claim 1, to an individual in need of preventing condyloma acuminatum or HPV infections. 